SYSTEM FOR SPUTTERING COMPOSITIONS ONTO A SUBSTRATE

Abstract: An apparatus for producing a composite film of several elements on a substrate (25) such as a magnetic disk for a disk drive. The apparatus includes a sputtering chamber (30) and at least a first and second sputtering magnetrons (621 - 624) associated with a first target comprising a first component and a second target comprising a second component. A rotating chuck (50) is positioned in the chamber opposite the targets and a substrate (25) is mounted thereon and rotated so that target elements are simultaneously sputtered achieving a multi-component film coating on the surface of the substrate (25) with an even film gradient. In one embodiment, four targets each target comprising one of an element or composition of elements to be sputtered, are mounted abutting four magnetron assemblies (621 - 624).

Description: SYSTEM FOR SPUTTERING COMPOSITIONS ONTO A SUBSTRATE CROSS-REFERENCE TO RELATED APPLICATION(S) BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to the development of magnetic recording media for use in Winchester-type hard disk drives. Specifically, the invention relates to a method and apparatus for depositing and evaluating different coating compositions on a disk substrate for eventual use in a Winchester-type hard disk drive. 2. Description of the Related Art With the advent of ever more powerful hardware in the computer industry, the need for increased storage capacity in the storage devices used with computers, and the continuing trend toward decreased physical size of storage devices while increasing capacity, particularly with Winchester-type hard disk drives, manufacturers continually seek new ways to increase storage density in decreased size. A critical component in increasing the storage capacity of such devices is the magnetic storage capacity of the recording media or "hard disk" used in such devices, and the accuracy with which data may be transferred to and from the media. Several factors are important in designing magnetic recording media. Among such factors is a high coercivity, especially where high magnetic recording density is desired. Generally, the stronger the magnetic coercivity of the disk, the higher the flux density achievable on the disk, and hence the higher the data bit density per unit area. Another important factor in the design of recording media is the resistance of the media to corrosion and wear. Corrosion and wear of the disk media occurs over the life of the drive and results from constantly reading from and writing to the media, incidental contact between the read/write heads and the media, and contamination within the controlled environment of the disk drive where the disk is located. Manufacturers of recording media use various techniques to produce a magnetic recording layer on a disk substrate. One such technique is sputter deposition. Sputter deposition is popular due to the manufacturing advantages available with conventional sputtering processes. Generally, sputtering is performed in an evacuated chamber using an inert gas, typically argon, with one or more substrates either remaining static during deposition and being rotated about the target (a "planetary" system) , or being transported past the target (an "in-line" system) . Fundamentally, the technique involves bombarding the surface of a target material to be deposited as the film with electrostatically accelerated argon ions. Generally, electric fields are used to accelerate ions in the plasma gas, causing them to impinge on the target surface. As a result of momentum transfer, atoms and electrons are dislodged from the target surface in an area known as the erosion region. Target atoms deposit on the substrate, forming a film. By applying several different layers of material over the substrate, characteristics such as wear and magnetic intensity can be optimized. Several compositions for magnetic recording media have been developed in order to enhance certain characteristics of the media, such as coercivity, or to suppress other unwanted effects of the media, such as waveform modulation. Typically, the disk substrate material comprises glass, nickel-phosphorus plated aluminum disks, or ceramic materials. A substrate may first be supplied with a chromium layer overlying the substrate surface. The chromium layer is generally 50θA-200θA thick. A magnetic layer, which may be a magnetic alloy comprised of so-called "hard magnetic materials" such as alloys of nickel, cobalt, or iron. Generally, for a magnetic layer comprising a sputtered film of cobalt-chrome-tantalum (CoCrTa) , the film is deposited to a thickness in the range of 30θA-85θA. Finally, a carbon overcoat layer is provided to a thickness of about 25θA-35θA. In addition to achieving high film deposition rates, sputtering offers the ability to tailor film properties to a considerable extent by making minor adjustments to process parameters. Of particular interest are processes yielding films with specific crystalline microstructures and magnetic properties. Consequently, much research has been conducted on the effects of sputtering pressures, deposition temperature, and maintenance of the evacuated environment in large scale sputtering systems to avoid contamination or degradation of the substrate surface before film deposition. In addition, much research has been conducted in the field of coating compositions to improve selected coating characteristics. Many approaches to tailoring film properties have focused on manipulating the crystalline microstructure by introducing other elements into the alloy composition. For example, Shiroishi, et al., "Read and Write Characteristics of Co-Alloy/Cr Thin Films for Longitudinal Recording", IEEE Trans. Maαn.. Vol. MAG-24, 2730-2, 1988, and U.S. Patent No. 4,652,499, issued March 24, 1987 to J. K. Howard and assigned to IBM, relate to the substitution of elements such as platinum (Pt) , tantalum (Ta) , and zirconium (Zr) into cobalt- chromium (CoCr) films to produce higher coercivity and higher corrosion resistance in magnetic recording films. Alloys of cobalt, nickel and chromium deposited on a chromium underlayer (CoNiCr/Cr) are highly desirable as films for magnetic recording media such as disks utilized in Winchester-type hard disk drives. CoCr alloys with tantalum (CoCrTa) are also particularly attractive films for magnetic recording media. For example, it is known in the prior art to produce CoCrTa films by planetary magnetron sputtering processes using individual cobalt, chromium and tantalum targets or using cobalt-chromium and tantalum targets. However, as noted below, prior art deposition systems were unable to produce disks having fully functional capability for use in Winchester-type disk drives. Fisher, et al., "Magnetic Properties and Longitudinal Recording Performance of Corrosion Resistant Alloy Films", IEEE Trans. Maσn.. Vol. MAG 22, no. 5, 352-4, Sept. 1986, describe a study of the magnetic and corrosion resistance properties of sputtered CoCr alloy films. Substitution of 2 atomic percent (at.%) Ta for Cr in a Co-16 at.% Cr alloy (i.e., creating a Co-14 at.% Cr-2 at.% Ta alloy) was found to improve coercivity without increasing the saturation magnetization. In particular, a coercivity of 1400 Oe was induced in a 400 A film. In addition, linear bit densities from 8386 flux reversals/cm to 1063 flux reversals/cm (21300 fci to 28100 fci) were achieved at - 3 dB, with a signal-to-noise (SNR) ratio of 30 dB. Moreover, corrosion resistance of CoCr and CoCrTa films was improved relative to CoNi films. U.S. Patent No. 4,940,548, issued on August 21, 1990 to Furusawa, et al., and assigned to Hitachi, Ltd., discloses the use of Ta to increase the coercivity and corrosion resistance of CoCr (and CoNi) alloys. CoCr alloys with 10 at.% Ta (and chromium content between 5 and 25 at.%) were sputtered onto multiple layers of chromium to produce magnetic films with low modulation even without texturing the substrate surface and highly desirable crystalline microstructure and magnetic anisotropy. Magnetron sputtering processes have been developed which have been somewhat successful in achieving high throughput manufacture of sputtered magnetic media. For example, U.S. Patent Nos. 4,735,840 and 4,894,133 issued to Hedgcoth on April 5, 1988 and April 16, 1990, respectively, describe a high volume planar d. c. magnetron in-line sputtering apparatus which forms multilayer magnetic recording films on disks for use in Winchester-type hard disk technology. The apparatus includes several consecutive regions for sputtering individual layers within a single sputtering chamber through which preheated disk substrates mounted on a pallet or other vertical carrier proceed at velocities up to about 10 mm/sec (1.97 ft/min) , though averaging only about 3 mm/sec (0.6 ft/min). The first sputtering region deposits chromium (1,000 to 5,000 A) on a circumferentially textured disk substrate. The next region deposits a layer (200 to 1,500 A) of a magnetic alloy such as CoNi. Finally, a protective layer (200 to 800 A) of a wear- and corrosion-resistant material such as amorphous carbon is deposited. While high throughput systems have a number of advantages in manufacturing large quantities of sputtered media, initial runs of experimental deposition coatings tend to be economically unfeasible. When conducting trail runs of new components in an in-line system, each target of chrome or magnetic materials can cost on the order of $1500-2000. Target materials of alloy material can be much higher. The apparatus described in co-pending United States Application Serial No. 07/686,886, requires up to one MWatt of power during sputtering operation. Further, to test variations in the magnetic layer composition, magnetic alloy targets must be specially formulated for use in prior art drives. Thus, manufacturing disks with untested alloys or experimental coatings is an expensive proposition. While devices for sputtering various compositions of coatings onto individual disk substrates exist in the prior art, such systems have heretofore been incapable of providing a drive-ready disk suitable for real-world testing. Most such planetary systems involve target handlers which change the position, but not the orientation of the disk with respect to the targets. In addition, such systems are not optimized to provide an even composition gradient over the substrate surface. As such, the film distribution results in a thicker coating at the center of the disk and a thinner coating adjacent the edges of the disk. Disks suitable for actual use in drives must have uniform thickness distributions over the disk surface area to allow the read/write heads to move smoothly over the disk surface. SUMMARY OF THE INVENTION Thus, an object of the invention is to provide a method and apparatus for economically testing new magnetic media coating compositions in a real-world disk drive environment. A further object of the invention is to provide a method and apparatus for developing a single sputtered magnetic recording disk. Yet another object of the invention is to provide a method and apparatus for testing new coating compositions in a disk drive. A further object of the invention is to provide the aforesaid method and apparatus includes means for quickly and economically altering the composition of the magnetic coating layers deposited on the disk surface. Yet another object of the invention is to provide a unique method and apparatus for simultaneously depositing a plurality of coating components onto a disk substrate. These and other objects of the invention are provided in an apparatus for producing a magnetic disk for a disk drive. In general the apparatus includes a sputtering chamber; and at least a first and second sputtering magnetrons associated with a first target comprising a first component and a second target comprising a second component, for simultaneously sputtering a multi-component coating onto the surface of the disk in the chamber with an even distribution over the circumference of the disk. In a further aspect, a rotating chuck is positioned in the chamber opposite the targets for mounting a substrate thereon. In a further aspect, four targets, each target comprising one of the element or composition of elements to be sputtered, are mounted abutting four magnetron assemblies. In addition, a shield structure is mounted so as to provide relative isolation between the respective target and magnet assembly structures such that each target and magnet assembly is exposed to approximately one-quarter of the disk at any given time. In yet another aspect of the invention, a method for manufacturing a disk for a disk drive is provided. The method comprises the steps of: placing a disk in a sealed environment opposite at least three sputtering magnetrons; heating and rotating the disk; and simultaneously depositing at least three coatings onto the disk by energizing the magnetrons wherein only a fraction of the disk is exposed to any one magnetron at one time. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of the apparatus for manufacturing a magnetic recording disk for a disk drive in accordance with the present invention. Fig. 2 is a plan view of the rear portion of the apparatus in accordance with the present invention. Fig. 3 is a perspective partial cutaway view of the apparatus for manufacturing a disk drive in accordance with the present invention. Fig. 4 is a cross-sectional view along line 4-4 of the apparatus in Fig. 2. Fig. 5 is a partial, perspective, exploded view of the certain internal components of the apparatus in accordance with the present invention. Fig. 6 is a cross-sectional view along line 6-6 of the apparatus in Fig. 2. Fig. 7 is a partial, cross-sectional view of the apparatus of the present invention illustrating two different types of magnetron cathode assemblies which may be used in accordance with the present invention. Fig. 7A is a partial, cross-sectional view of the apparatus of the present invention illustrating an alternative magnetron assembly for use in accordance with the present invention. Fig. 8 is a plan view of one embodiment of the sputtering shield which may be used in the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENT In accordance with the present invention, a unique method and apparatus for manufacturing individual magnetic recording disks is provided. The apparatus and method facilitates experimentation with multiple coating structures in the manufacture of sputtered magnetic disks by allowing economical manufacture of such disks with various novel compositions sputtered thereon. The apparatus provides a economical and efficient manner in which testing of such novel disk coating compositions may occur under real world environmental conditions, such as in a working hard disk drive. In Fig. 1, a perspective view of disk sputtering apparatus 10 is shown. Apparatus 10 includes a housing generally defined by a cylindrical body 12, a front plate 16, and a rear plate 14, all manufactured out of aluminum. Front plate 16 and rear plate 14 are secured to cylindrical housing 12 by a plurality of socket head machine screws 18 (shown only in respect to front plate 16 in Fig. 1) . Grip handles 20,22 are provided to allow for removal of front plate 16 during maintenance of apparatus 10. As shown in Figs. 1 and 2, a door 40 is mounted to front plate 16 to allow access to the interior of the housing. Door 40 is mounted to front plate 16 by a hinge assembly 42, which includes hinge 43, hinge block 44, and hinge pin 45. A motor assembly including motor 55, coupling 59, ferro-fluidic feedthrough 53, and motor mount plate 56, is mounted on door 40 to rotate a chuck assembly, discussed below, on which a disk substrate 25 is provided into sputtering apparatus 10. Three clamps 46 1 -46 3 are used to secure door 40 to the front plate 16. Each clamp 46 is comprised of a clamp spacer arm 47 secured to front plate 16 by a hex jam nut 48. A toggle shoe clamp 49 is secured in the spacer arm 47 and clamps door 40 to front plate 16. A handle 38 is provided on door 40 to allow the user to access the interior housing by rotating door 40 about hinge pin 45. Three view ports 27, 28, and 29 are provided on apparatus 10 to allow the system user to visually monitor processing within apparatus 10. Each view port is comprised of a window clamp ring 26 which secures a 1.5 millimeter thick glass window 24 which is manufactured from calcium fluoride or Pyrex ® . 0-rings (not shown) are provided between clamp ring 26 and glass substrate 24, and each clamp ring for ports 27,28,29 is secured to door 40 or cylindrical housing 12 by socket head machine screws 27a, 28a, and 29a, respectively. As will be understood from a review of the instant specification, ports 28 and 29 are positioned symmetrically on opposite sides of cylindrical body 12 and, because of this location, are closer to the sputtering environment within the housing. As a result, ports 28, 29 are fitted with window shutter assemblies 160a-b, respectively to protect windows 24 from stray sputtering atoms. Each sputtering assembly 160a-b includes a shutter 161a, coupled to a handle 162a-b by a shaft 163 fitted through body 12 by coupling 164a-b. As will be readily understood, rotation of handles 162a, 162b, correspondingly rotates window shutters, such as shutter 161a, toward or away from windows 24b,24c. Four one-inch through-holes are provided on the surface of front plate 16. The through-holes are filled by 1-inch diameter plugs 90 and a rear flange 91 (Fig. 4) , located in antechamber 32 and secured to rear plate 16 by washer 92 and socket head machine screw 93. An 0- ring 94 is provided in flange 91 to ensure a sealed environment in antechamber 32 and to prevent external pressures from affecting the sputtering process. Two coolant elbow couplings 98 2 . 98 3 are secured to rear wall 16 and feed through front plate 16 to supply coolant material to the interior of the housing, as will be discussed in further detail below. Electrical feedthrough 23 is provided on door 40 to allow the electrical conduits for the heater system and substrate bias supply (discussed below) to be provided to the interior cavity of the system. Sputtering apparatus 10 may be mounted on a 8-inch diameter pipe mount 15 by a base flange 13 secured to pipe mount 15 by socket head bolts 17 and hex-nuts 19. (Fig. 3) . A filter screen 11 is provided on a mounting flange 11A in pipe mount 15. At the base of pipe mount 15 is a roughing pump and an 8-inch diameter cryogenic evacuation pump which serve to evacuate both antechamber 32 and sputtering chamber 30 when sputtering of disk 25 is to begin. Naturally, door 40 needs to be secured in a closed position (shown in Fig. 4) , prior to evacuation of apparatus 10. The internal components of sputtering apparatus 10 will be described with reference to Figs. 3 through 6. Figure 3 is a partial, perspective cutaway view of apparatus 10. Figure 4 is a cross-sectional view along line 4-4 of Figure 2. Fig. 5 is an unexploded view of the sputtering assembly, and other internal components of apparatus 10. Fig. 6 is a top view along line 6-6 in Fig. 2. The interior of apparatus 10 is divided into sputtering chamber 30 and antechamber 32 by an inner chamber wall 34 which is secured to front plate 16 by socket head cap bolts 33 provided through spacers 36. Inner chamber wall 34 has a circular aperture 35 included therein which allows disk 25 to be exposed to sputtering chamber 30 when door 40 is in a closed position (as shown in Figs. 1, 2 and 4) . Also provided adjacent sputtering chamber 30, as shown in Figs. 2 and 3, is a sputtering magnetron assembly 60. Magnetron assembly 60 includes four sputtering magnetrons 62 1 -62 4 . Shield assembly 70 is provided adjacent the sputtering 'magnetron assembly 60 to isolate the flux of each particular sputtering magnetron 62, -62 4 (when the system is energized) to one-fourth of the surface area of a particular disk substrate 25 when substrate 25 is provided adjacent to sputtering chamber 30 and exposed to the energized assembly 60. In sputtering chamber 30, magnetron assembly 60 is secured to rear plate 14 by socket head machine screw 61. Rear wall 14 contains an aperture slightly larger than that provided for door 40 to allow sputtering magnetrons 62 1 -62 4 to be provided into sputtering chamber 30. Shield assembly 70 is secured to rear wall 14 by a mounting flange 71 which is coupled to rear wall 14 by socket head machine screws (not shown) . As shown in Figs. 3-5, shield assembly 70 includes a cylindrical main portion 72 having one end abutting sputtering magnetron assembly 60, and a second end positioned adjacent inner chamber wall 34. The second end includes an interior flange 73 which defines an aperture opening 74 corresponding to aperture 35 in inner wall 34. Four intersecting shield walls 76^-76 4 are mounted in cylindrical casing 72 to provide a cross-hair shield arrangement for sputtering magnetrons 62 1 -62 4 . Intersecting shield walls 76,-76 4 divide cylindrical casing 72 into four separate regions 77 1 -77 4 , with each region 77 1-4 corresponding to a single magnetron 6 1 _ 4 , respectively. Thus, when disk substrate 25 is positioned adjacent the sputtering shields 76, one quarter of the surface area of disk substrate 25 is exposed to each individual magnetron at a particular time. As will be discussed below, rapidly rotating the disk substrate 25 and simultaneously energizing the magnetrons, a magnetic recording disk can be manufactured which is suitable for use in a working disk drive. By varying the sputtering energy, target composition, and/or shielding, any number of optimal element compositions may be achieved in a single layer film. As shown in Figs. 3, 4 and 6, motor 55 is coupled to a chuck assembly 50 and, as noted above, is mounted on door 40 to provide selective rotation of chuck assembly 50. As detailed in Fig. 4, motor 55 is coupled to door 40 by a ferro-fluidic feedthrough 53 secured to door 40 by socket machine head screws 54 with an 0-ring 56a providing a seal between feedthrough 53 and door 40. A motor mount 56 is secured to feedthrough 53 and encases motor coupling 58 which may be comprised of a piece of serrated aluminum, secured with two set screws, allowing flexibility in the coupling of the output shaft 55A of motor 55 to the output shaft 53a of the ferro- fluidic feedthrough 53 for alignment of the shafts. A coupling 59 secures motor mount 57 to motor 55. Chuck assembly 50 includes disk holder 52, secured to an insulator post 51 by four set screws (not shown) . A washer 52A secures disk 25 in place with a buttonhead hex socket machine screw 51A. Shaft 53a of feedthrough 53 is coupled to insulator post 51, which is secured to disk holder 52 when disk 25 is secured in disk holder 52. Motor 55 is capable of generating disk rotation up to 600 rpm. As shown in Figs. 3 through 6, sputtering magnetron assembly 60 is comprised of four sputtering magnetrons 62 1 -62 4 which are secured to rear plate 14 by a cathode mounting plate 63. Mounting plate 63 is bolted to rear plate 14 by socket head machine screws 61. A water jacket 64 surrounds cathode mounting plate 63, and two 0-rings 63a, 63b are provided to ensure a watertight seal from the circulating coolant water in sputtering cathodes 62 1 -62 4 . Each sputtering magnetron 62 1 -62 4 is secured to cathode mounting plate 63 by a hex machine screw 62a. Gas channel 66 is provided in cathode mounting plate 63 and is coupled to an elbow fitting 65. Elbow 65 is coupled to a gas supply, allowing sputtering gas, such as argon, to be provided to sputtering chamber 30 and antechamber 32. Water supply outlets 67 are provided to couple a liquid coolant such as water, to each sputtering magnetron 62 1-4 . A cover 68 encases sputtering magnetron assembly 60 and includes cutout regions (not shown) to allow for coupling of external gas and water supply lines to conduits such as elbow 65 and inlet 67. (It should be understood that with respect to sputtering magnetrons 62, two fittings such as elbow 65 are required -- one as an inlet, one as an outlet -- to provide coolant circulation through the magnetrons.) A shutter 80 is provided to allow for selective exposure of disk substrate 25 to the sputtering magnetron assembly 62. Exposure shutter 80 is coupled to a shutter mount 82 which is secured to rear plate 14 by a rotary ferro-fluidic feedthrough 84, to provide isolation between sputtering chamber 30 and the external environment. A handle 86 is coupled to the ferro fluidic feedthrough 84 to allow a system operator to selectively rotate exposure shutter 80 between an open, exposure position and a closed, shield position, as shown in Fig. 3, to expose or shield disk 25. As shown in Figs. 3 and 5, holes 78,79 are provided in shield assembly 70, and inner chamber wall 34, respectively, to ensure pressure equalization in sputtering chamber 30 and antechamber 32. In practice, prior to installation of holes 78,79, when sputtering gas is introduced through channel 66 and shutter 80 is closed, a pressure differential between the interior of sputtering assembly 70 and the rest of the housing interior developed. Thus, opening of shutter 80 would cause the pressure within the chamber to change, a condition which is unacceptable because sputtering pressure is a characteristic which must be optimized prior to exposing the disk to the sputtering plasma. As shown in Figs. 3-6, two separate cooling lines 95*^ and 95 2 are provided in sputtering chamber 30 and antechamber 32, respectively, and surround shield assembly 70. Coolant line 95 is connected to a circulating coolant supply by an output coupling 96-^ which is provided through rear plate 14. An 0-ring 97 separates coupling 96, from rear plate 14, and an elbow fitting 98 is coupled to the exterior of rear plate 14. A second coupling (not shown) is provided at a location horizontally opposite feedthrough 84 thus providing a coolant flow path from coupling 96,, around shield assembly 70 in a coil-like manner, to the second coupling (not shown) . Second coolant line 95 2 is provided around circular aperture 35 in innerchamber wall 34. Second coolant line 95 2 runs from coupling 96 2 to coupling 96 3 , both provided through rear chamber wall 16, and secured to elbow fittings 98 2 and 98 3 , respectively. Coolants are necessary to maintain sputtering magnetrons 62 1 _ 4 and shield assembly 70 at a constant temperature. Magnetrons 62 1-4 generate heat when coupled to a power supply to energize the argon gas to a plasma state. Power on the order of lkW is provided to the cathode of each sputtering magnetron, generating the sputtering plasma. As such, a great amount of heat is generated which must be removed by the system's circulating coolant flow. A heating assembly 100 (Figs. 3, 6, and 7) is provided to raise the temperature of substrate 25 on chuck assembly 50. Heating the substrate contributes to increasing the quality of films sputtered onto disk substrates. Heating assembly 100 is comprised of a housing 101 coupled by crossbeam 102 to an insulator 103 (such as Delrin ® ) provided on a heater mount assembly 104 secured in door 40 by screws 106. Housing 101 supports a reflector 105 and a heating element 107, which act in concert to provide radiant heat to the rear of disk holder 52. A heater power supply (not shown), generally separate from the sputtering magnetron power supply, is coupled via electrical leads to heating element 107 provided the electrical feedthrough 23. Heating assembly 100 thus may raise the temperature of substrate 25 to a temperature of about 300°C. As shown in Fig. 6, an infrared detector assembly 110 is provided on door 40 to allow the system operator to monitor the temperature of disk 25 and disk holder 52. Detector assembly 110 is comprised of a window fitting 111 which is secured to door 40 by a socket head screw 112. A piece of calcium fluoride glass 113 is positioned in the end of window fitting 111 and secured thereto by a cap 114, two 0-rings (not shown) , are included for seating the assembly, with one positioned between cap 114 and glass 113, and one between glass 113 and fitting 111. A detector 115, such as a Thermopile Detector with KBR window, manufactured by Dexter Research Center, Inc., and accompanying amplifier, lays in fitting 111, is suitable for use in one embodiment. Essentially, such detector 115 is a photodiode with silicon windows which measures the temperature of substrate 25 to allow the system operator to calibrate the temperature lamp and the desired temperature of the disk. A bore 116 in door 40 is present to allow detector 115 to be selectively inserted and retracted by the user. Also shown in Fig. 6 is a coupling assembly 120 for a capacitance manometer, positioned adjacent shield assembly 70. The manometer allows the user to monitor the gas pressure within sputtering chamber 30. A capacitance manometer of the type manufactured by MRS Instruments, Inc. is suitable for use with the apparatus. The coupling assembly includes a T-fitting 121 secured to apparatus 10 by a clamp fitting 122 including a center ring 123 and an O-ring 124 clamped thereabout. A conduit 125 provides the gas pressure present in assembly 70 directly to T-fitting 121. The capacitance manometer may thereafter be positioned adjacent to the apparatus and coupled to either outlet of the T-fitting. As noted above, the pressure measured by the capacitance manometer will be stabilized over the interior of apparatus 10, allowing the user to precisely control the sputtering pressure prior to, and during, sputtering. An electrode assembly 126 (shown in Fig. 4) is provided to allow the system operator to bias disk substrate 25 by applying a bias potential to disk holder 52 during the coating process. Biasing of the substrate has been found useful in a number of coating applications. As shown in Fig. 4, biasing assembly 126 comprises a post 127 generally manufactured from a high- durability insulator, such as ceramic, and a copper electrode 128 which has a arcuate shape (with curvature arc going into the page) allowing the electrode to brush against disk holder 52 while disk holder 52 is rotating, making sufficient contact therewith in a spring-like fashion to bias disk substrate 25, while not providing significant resistance to the motor assembly. Fig. 7 is a partial enlarged cross-section view from the same perspective as Fig. 6 detailing the composition of sputtering magnetron assemblies 62a-d. Shown in Fig. 7 are two different cathode designs, one for a magnetic coating target, the other for a non- magnetic coating target. It should be understood by those skilled in the art that the particular arrangement, placement and composition of the assemblies is dependent on the materials utilized and the coating structure which is being manufactured. Assembly 62 may be used with a magnetic coating target material, such as cobalt or its alloys, or a composite thereof. Assembly 62 4 in Fig. 7 is an example of a cathode assembly which is suitable for use with a nonmagnetic target material. With regard to the description thereof, assemblies 62 and 62 4 have similar parts; thus, like parts have identical reference numerals, with those parts peculiar to each assembly delineated by subscripts. As shown in Fig. 7, assemblies 622, 62 4 each include an anode 131 which is secured to cathode mounting block 63 by hex nut screw 132. The cathode assembly includes a cathode body 133, which is coupled to cathode mounting plate 63 by a hex nut machine screw (not shown) in insulator ring 135. Insulator ring 135 separates cathode body 133 from cathode mounting plate 63. O-ring 141 is provided in insulator ring 135 to provide a tight seal between sputtering chamber 30 and the external environment. O-ring 139 is provided between cathode body 133 and insulator 135. In assembly 622 cathode body 133 houses disk-shaped magnets 145 2 and 145 2 and ring shaped magnets 146 2 and 146 2 . The permanent magnets 145 and 146 are magnetically energized to have a force F in the direction shown in Fig. 7. (It should be readily understood that the magnetic polarity could be reversed without affecting the performance of the magnetrons.) Similarly, in assembly 62 4 , cathode body 133 houses disk shaped magnet 145 3 and ring-shaped magnet 147. A coolant fitting 140 is mounted in cathode body 133 and provides a conduit to coolant channel 144, formed adjacent sputtering target 1382- Coolant is provided through fitting 140 to channel 144 to circulate therethrough and out a separate fitting (not shown) , identical to fitting 140, to maintain a nominal temperature level in assemblies 622"62 4 thereby preventing damage to the sputtering magnetrons. A rear pole piece 136 is provided to secure magnets 145, 146 and 147 into cathode body 133. A cathode nut 137 secures target 1382 or 138 2 to the cathode body 133. For the non-magnetic assembly 62 4 , target material 138 2 is much thicker than the magnetic target material 1382 in cathode assembly 622- In addition, approximately one-half of the permanent magnetic pieces used in cathode assembly 62 2 are required in assembly 62 4 , although the direction of permanent magnetization therein are the same. As will be understood by those skilled in the art, a d.c. bias is applied to the cathode assembly to induce sputtering. In accordance with well understood principles, the bias may be in the range of 300-700V and, in the pressure of argon gas, will induce sputtering from the target. Magnets 145 assist in increasing the sputtering rate by maintaining more electrons in the sputtering plasma close to the sputtering target. Therefore the target materials are dislodged by the accelerated argon ions and impinge the disk substrate positioned opposite the target materials. Figure 7A shows an alternative embodiment of the magnetic cathode assembly 61, a suitable for use in the apparatus. Like parts have like designations with the assembly presented in Figure 7. In Figure 7a, cathode body 133a is thicker than body 133 of assembly 62,, and the bores housing magnet ' s 145, 146 have been provided through the entire width of the body. To improve conduction of magnetic flux to the area adjacent the target material, stainless steel plugs 133a, 133b are provided adjacent magnets 146. Plugs 133a, 133b are preferably comprised of magnetically permeable stainless steel, such as series 420 or 430 stainless steel. Two rear pole pieces 136a, 136b are placed abutting magnets 146 2 and 145 2 , respectively. Fig. 8 shows an alternate embodiment for employing an additional shield 150 in shield structure 70. Shield 150 is provided to optimize sputtering of compositions where one element sputters at a slower rate than others, such as a cobalt-chrome-tantalum coating such as those discussed in the Background section. Specifically, shield 150 ensures that, in cases where small percentages of a particular element are desired in a particular composition, oxides will not form as a result of interaction between the sputtering element and background of water vapor in the system due to the lower sputtering rate. In coatings such as those discussed in the background section of the application, because tantalum is present in small doses, it would sputter at a much lower rate than other elements in the compositions. In such cases, the amount of water vapor present in the system can cause formation of unwanted Ta0 2 . To eliminate Ta0 2 formation, tantalum can be sputtered at a higher rate over a reduced area to achieve the same relative mix of components. As will be readily understood, the shield structure may be adapted for use with different coating materials at different rates where necessary to eliminate oxide formation. Uses of sputtering apparatus 10 of the present invention may be illustrated as follows. A coating of Co-Cr-Ta with respective percentages of 10.5%-4%-85.5% may be generated by providing assembly 622 w ^- tn a target material of Co, assembly 62 2 with a target material of Cr, assembly 62 3 with a target material of Ta, and assembly 62 4 with a target material of carbon. A substrate is mounted on chuck and rotated at about 300rpm while the sputtering chamber is evacuated to a pressure of 5 x 10' 7 Torr, and argon gas is allowed to flow into the chamber to backfill to 1.0 mTorr. Heating assembly 100 is activated to heat the substrate to a temperature of approximately 200-250C 0 . When the optimum sputtering environment is reached, a bias of 200-800V is applied to the sputtering assemblies and sputtering induced. When the sputtering environment is established, shutter 80 is rotated to expose the disk substrate to the sputtering environment. Typically, such exposure lasts approximately 10 minutes before the shutter is returned to the "closed" position. It should be understood that the factors set forth above will vary based on the type of coating being prepared. A drive- ready disk, having the capacity to be recorded to and read from is thus produced. It should be noted that the above example merely illustrates a single use of the sputtering apparatus and method. A primary advantage of the system is the ease with which any number of parameters -- temperature, pressure, power, target composition, etc. -- may be altered to study the effect of such change on the composition and characteristics of the sputtered films. Many features and advantages of the present invention will be apparent to those skilled in the art. Numerous modifications are contemplated as being within the scope of the specification and the accompanying claims.

Claims: CLAIMS 1. An apparatus for producing a magnetic disk for a disk drive, the disk including a surface, comprising: a sputtering chamber; means for simultaneously sputtering a multi- component coating onto the surface of the disk in the chamber from a first target comprising a first component and a second target comprising a second component, wherein the coating is applied to the surface with an even distribution over the circumference of the disk; and means for controlling the means for sputtering. 2. The apparatus of claim 1 wherein the multi- component film comprises a relative mixture of the components in a single film layer. 3. The apparatus of claim l wherein the means for simultaneously sputtering includes at least a first and a second magnetrons respectively associated with the first and second targets, and positioned in the sputtering chamber and separated by a shield, and a rotating chuck on which the disk is mounted opposite the magnetrons. 4. The apparatus of claim 1 wherein the means for sputtering simultaneously sputters at least four components on the surface of the disk, and further includes at least a third and a fourth target, respectively associated with a third and a fourth magnetron. 5. The apparatus of claim 4 wherein the sputtering magnetrons separated by a sputtering shield, and further includes a rotating chuck for mounting the disk adjacent the sputtering magnetrons, wherein one quarter of the disk surface is exposed to one of the magnetrons at a given time. 6. The apparats of claim 5 wherein the means for controlling comprises: a power source coupled to the sputtering magnetrons; means for driving the rotatable chuck; and an exposure shutter, positioned between the surface of the disk and the sputtering magnetrons. 7. The apparatus of claim 1 further including means for heating the disk in the sputtering chamber. 8. The apparatus of claim 6 further including means for sensing the temperature of the disk in the sputtering chamber. 9. The apparatus of claim 1 further including means for evacuating the sputtering chamber. 10. The apparatus of claim 1 further including means for providing a sputtering gas into the sputtering chamber. 11. Apparatus for depositing at least two coatings on a disk substrate, comprising: a sputtering chamber, the chamber having at least two targets comprised of different materials to be sputtered positioned therein; and a rotating chuck, positioned in the chamber opposite the targets, including means for mounting a substrate thereon. 12. The apparatus of claim 11 wherein the chamber further includes a shield separating the targets such the material from the target is incident on only a portion of the disk at a particular time. 13. The apparatus of claim 11 further including a heating element positioned to heat a substrate in the chuck when the chuck is rotating. 14. The apparatus of claim 13 further including a temperature sensor positioned to detect the temperature of the substrate. 15. The apparatus of claim 11 further including a vacuum pump for evacuating the sputtering chamber. 16. The apparatus of claim 11 further including a supply of sputtering gas and means for regulating the supply of sputtering gas to the sputtering chamber. 17. The apparatus of claim 11 further including a pressure sensor coupled to the sputtering chamber. 18. The apparatus of claim 11 further including a cooling system disposed adjacent the sputtering chamber and coupled to a coolant supply thereby circulating coolant fluid in the sputtering chamber. 19. An apparatus for producing a magnetic disk for a disk drive, the disk including a surface, comprising: a sputtering chamber; means for rotating the disk within the sputtering chamber; means for simultaneously sputtering at least two coatings to the disk in the chamber wherein the coatings are applied to about one-quarter of the disk surface at one point in time; and means for controlling the means for sputtering. 20. The apparatus of claim 19 wherein the means for sputtering comprises a sputtering magnetron assembly including four targets, each target comprising one of the coatings to be sputtered, mounted abutting a magnet assembly, and a shield structure to provide relative isolation between the respective target and magnet assembly structures such that each target and magnet assembly is exposed to approximately one-quarter of the disk at any given time. 21. An apparatus for manufacturing a disk, comprising: a single sputtering chamber having means for rotatably supporting the disk within the chamber; means for rotating the means for rotatably supporting; means for applying a multi-component coating to the disk; and means for controlling the deposition of the coating on the disk and the means for rotating. 22. An apparatus for producing a magnetic disk, comprising a housing having a generally cylindrical shape, a first end and a second end, the housing defining a sealed chamber; a rotating chuck, positioned at one end of the housing; a motor, coupled to the rotating chuck; four sputtering targets, positioned at the opposite end of the housing and opposite the rotating chuck; four sputtering magnetrons respectively associated with the sputtering targets; a vacuum pump, coupled to the sealed chamber; means for exciting the sputtering targets; and means for activating the motor. 23. A method for manufacturing a disk for a disk drive, comprising: placing a disk in a sealed environment opposite at least three sputtering magnetrons; rotating the disk; and simultaneously depositing at least three coatings onto the disk by energizing the magnetrons wherein only a fraction of the disk is exposed to any one magnetron at one time. 24. A method for manufacturing a disk for a disk drive, comprising: rotating a disk substrate in a sputtering atmosphere; depositing a magnetic coating onto the surface of the substrate; and depositing a overcoat layer onto the magnetic coating.

Inventors: BONIGUT JOSEF, HOLLARS DENNIS R, WARD KEITH A, BONIGUT, JOSEF, HOLLARS, DENNIS, R., WARD, KEITH, A.
Applicants: CONNER PERIPHERALS INC, CONNER PERIPHERALS, INC.
Application year: 1994
Main classification: C23C14
IPC codes: C23C14, G11B5, H01F41, H01J37, H01L21